Indexed control



March 24, 1953 R. J. AUST ETAL 2,632,830

INDEXED CONTROL Filed Dec. 27, 1950 l Faber/Jim! Waller [fie/f 4 TTOR/VE Y Patented Mar. 24, 1953 UNITED STATES PATENT OFFICE INDEXED CONTROL Robert J. Aust and Walter E. Peek, Indianapolis, I-nd., assignors toP. R. Mallory & Co-., Inc., In-- dianapolis, Ind., a corporation of Delaware Application December 27, 1950; SerialNo. 202,872

a plurality of predetermined steps of resistances for use with volume or tone control circuits.

According to one embodiment of the present invention, an indexing spring is adapted to cooperate wi-th, a molded rotor element whose undersurface has a plurality of integrally formed detents circumferentially equidistantly spaced therealong so as to provide means for obtaining a step by step resistance control in the device. In addition, there has also been provided means for obtaining predetermined indexed resistance steps by coating the resistance elements with sprayed silver to segment the resistive element circumferentially.

Accordingly, an object of the present invention is to provide a novel step by step control convertible from theusual type of control by effecting. simple structural changes therein.

Still another object of the present invention is to provide means for converting a continuously variable volume control to a stepby step volume control having a predetermined number of fixed resistor positions.

Another object of. the present invention is to provide control means afiording a predetermined fixed number of resistor elements adapted for use in volume or tone control circuits.

Still another object of the present invention is to provide a volume control which may be converted from a continuously variable device to one which is indexed to fixed positions.

Yet another object of the present invention is to provide an indexed control adapted for use in variable resistance type of circuitswherein an ordinary continuous control may be converted thereto by means of novel indexing means.

Another object of thepresent invention is to provide in: a volume control a component for varying: the resistance comprised of resistive sec- 2 tions separated by sprayed silver coatings whereby an indexed control maybe provided economically'.

The invention, in another of its aspects,- re'-- lates to novel features of the instrumentalities described herein for teaching the principal ob-- ject of the invention and to' the novel principles employed-in the instrumentalities, whether ornot these features and principles may be used'in the said object and/or in the said field.-

Other objects of the invention and the naturethereof will become apparent from the following description considered in connection with the accompanying figuresof. the" drawingand wherein like reference characters: describe elements of similar function therein and wherein" the scopeof the invention is determined rather from the ment shown in Fig. 1 taken along the line 2-2 thereof as adaptedto illustrate the construction of the rotor used therein;

Fig. 3 is a cross-sectional view of the'control as shown in the embodiment of Fig.- l' as takenalong the line 3-$ thereof and as adapted to show means for substantially containin'g th e index spring within the cup structure of the control;

Fig. 4 is an exploded view of an embodiment of the invention as adapted to illustrate the co'-* operative relationship of the several components thereof, and

Fig. 5' is a plan viewof' the resistance element which may be used in'the-control, said resistanceelement being. of the sectionalized sprayed silver type.

Generally speaking, the present inventionpro-' vides means for converting a' continuous type of control, such as a continuousresistor or potenti ometer control utilizable in a plurality of electrical circuits, to a step by step control whichmay be predeterminedly indexed soas-toope'r-ate much in the fashion of a control having several fixed resistors therein. The control utilizes the normal components heretofore used in providing a continuous type of control, yet with very little modification thereof is adapted to convert the said control to a step by step control device by means of novel, inexpensive structural changes. The invention includes as a component thereof an indexing spring which cooperates with the rotor of the control Whose underside is formed into a plurality of equidistantly spaced hemispherical detents. These detents provide means in cooperation with the index spring for obtaining fixed amounts of resistances. By this means, therefore, the indexing spring and detent components of the control have converted the control into a discontinuous type of control having a severality of equidistantly spaced fixed resistances. Moreover, provision has been made where, if it is not desired to use this type of indexing, an alternative means can be used whereby the resistance element itself may be converted into a series of discreetly spaced segments which are tantamount to affording a plurality of fixed resistance elements. The novel means provided is a resistance element whose face has been spacedly metallized or sprayed to encompass a plurality of discontinuous resistance elements and wherein the metal coatings thus formed act as terminals for the several resistance segments. Thus the present invention provides a simple and inexpensive means for converting a control having a substantially continuous resistance element into a predeterminedly indexed resistance type of control essentially providing a plurality of fixed resistors for use in tone or volume control circuits.

Referring now to the figures of the drawing, the variable resistance control device comprises an insulating base plate H? of Bakelite or other sheet insulating material, upon which may be supported a flat ring I l of insulating material, such as Bakelite fibre, having a surface I2 thereon of carbon paint or other resistance material. Base plate ii] is provided with a central aperture l3; a metal bushing l4 having a central aperture therein is clamped against the back of base plate ill by means of metallic spider [5 which is adapted to cooperate with a plurality of tongues formed at the open end of a shell 6. As seen, when the tongues of shell It fold over the spider element, the several components included within the said shell are tightly clamped therewithin.

Base plate member It has an arcuate resistive path formed on the surface of insulative ring 12 which is secured to the base by means of lugs 20, 2!, which are also adapted to position and stake the terminal ends 22, 23 of the control.

- The control device also includes an elongated rotatable element or shaft 24 extending through aperture I 3 in the base member and this shaft has a rotor body 3i] of insulating material molded to the inner end thereof. Rotor 3D includes two spaced surfaces 3| and 32. A transversely flexible and rotatable contactor 33 is interposed between surface 3! of rotor 30 and the arcuately mounted resistive element i2 in sliding relation therebetween. Contactor 33 is held on surface 3| for joint rotation with the shaft by means of keys, such as the diametrically opposite pro tuberances 34, 34' formed on surface 31 of the rotor which cooperate with the complementary slots 35, 35' on the contactor itself.

I As stated, the arcuately shaped resistive path 12 is formed on the underside of the base member I i). This arcuately formed resistive path may comprise carbonaceous material which is adhered to an arcuate insulative strip II, as seen. A short section has been cut from the resistive strip so that the surface does not form a complete circle, but is connected to terminals 22, 23. These terminals 22, 23 are connected to the ends of the resistive path 31, 38 and are stapled to the insulative strip or backing base member by means of lugs 25, 2|. Also concentrically positioned within the said arcuate resistive strip and firmly held to the base member is a contactor ring or electrical contactor surface so. To this contactor surface a third terminal 41 may be joined. In the present embodiment of the invention this terminal is formed as of one unit with the contactor surface, as by stamping the same from flat sheets of metal. The unit is held to the base member by depressing a reduced portion of the base member substantially midway of the connector or terminal through a hole 43 formed in the neck portion '52 of the base member and then crimping over a part of the said portion on the outside surface thereof. The contactor ring or electrical contactor id is stamped or pressed from a sheet of resilient material, such as Phosphor bronze, to form oppositely extending arcuate shaped spring contacting arms 44, 45 having on the inner ends thereof respectively contacts or wipers 41, 58. oppositely positioned from wipers 41, 48 on the other side of the shaft are brush-contacts 50, 5! formed on arc-like arms 52 and 53 respectively, formed by means of arcuate slots terminating with the ends within the main body of the contactor. As thus constructed, the contactor is held in a position on the rotor or rotatable element for sliding contact with the resistor surface and the brush collector surface.

The underside 32 of rotor 30 has been molded with a plurality of predeterminedly spaced hemispherical protuberances or detents 10, 10' etc. These protuberances formed on the undersurface 32 of the rotor may be positioned equidistantly circumferentially about the axis thereof and as hereinafter described, are adapted to cooperate with a resilient indexing spring so as to provide means for indexing or controlling the amount of rotation of the rotor 30 with respect to the resistance element 12 in the control. In this manner the continuous operation of the control may be adjusted so that in practicality a step by step advance in resistance may be afforded without complicated structure. Concentric with the undersurface of the rotor is a runner, or collar 8!, which, in cooperation with the casing of the control, is adapted to provide a stabilizing bearing so as to aid in prevention of any wobble in the shaft.

As stated, cooperating with the detents 10, 10 formed on the undersurface of the rotor 30 is an indexing spring 89 annularly formed so as to substantially have the configuration of a circular ring. To retain the indexing spring within shell or cup 87 of the control, a plurality of ears 85, 86 are struck from the shell to extend inwardly and provide means for anchoring the indexing spring 80. Indexing spring has formed therein a plurality of oppositely disposed slots 96, ct which are adapted to engage with the struck-out portions of the cup so as to substantially confine the spring therein. At approximately 90 from the slot portions of the indexing spring are hollows 92, 93. By this means indexing spring 80 is constructed in such fashion that although the slot portions lie flat against the cup or shell of the control, the segments therebetween on both sides of the slot portions are bowed so as to be substantially raised from the shell. The resilience thus obtained for the spring allows for a positive detent action between it and the molded detents of the rotor. It is thus seen that means have been provided for giving a positive indexing of the resistance element in a control. Thus a substantially continuous resistor has been converted to give predeterminedly fixed amounts of resistive values.

An additional method of providing the above indexing is shown in Fig. 5. There may be provided a resistance device to take the place of the continuously formed carbonaceous type of resistor element as described above. A resistive element may be formed for use with the control wherein various sectors of resistance may be obtained by spraying a coating of metal at definite portions 93, 98 of the carbonaceous resistance material. The metal, such as silver, so sprayed acts as terminals between the various sectors of resistance and affords means for obtaining a step by step type of resistance control. Thus in both constructions described above, a control is provided which instead of being continuously variable, is indexed to fixed positions.

The embodiments described above may be used in electrical circuits having particular requirements. For example, in tone control circuits there are two general ways for using the control. The first is to vary the resistance of an RC network, and the second is to vary the capacitance of the RC network. In the first case an indexed variable resistance type of circuit as shown in Figs. 1-4 is desirable. Here an ordinary volume control is provided with the present novel indexing means, so that the desired resistance values may be obtained at a desired indexing position. This type of contro1 has been exemplified above by the use of the rotor having molded detents cooperating with the indexing spring contained within the shell of the control. In the second type of case, shown in Fig. 5, where a limited amount of switching is required, the second method and means described above may be used. Here the various resistive sectors are obtained by spraying silver at certain portions of the carbonresistive material. This type of resistance element may then cooperate with the indexing detent and spring means described in the first embodiment of the invention. Thus, by the present invention, means have been provided for obtaining a basic, low cost control whereby a continuously variable control element may be indexed to fixed positions as desired.

The novel invention of an indexed control as described above is merely illustrative and not exhaustive in scope and since many widely different embodiments of the invention may be made without departing from the scope thereof, it is intended that all matter contained in the above description and shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. An electric control device comprising in combination, an enclosure shell containing components thereof and having an open end, a base member having a central opening out therethrough mounted in said open end portion of said shell, said member having an arcuate resistive path placed on the underside thereof, a contactor in sliding relation with said resistive path, a shaft passing through said opening in said base, mem-- ber, a rotor integrally molded to said shaft for, rotation therewith, said rotor having a multiplicity of spaced dentents formed thereon, means on said rotor for maintainin said contactor in slidingrelation with said resistive path on the. rota.- tion of said shaft, and spring indexing means cooperating with said detentsof said rotor for dividing the resistive path of said control into a predetermined number of indexed resistive steps.

2. An electric control device comprising in combination, an enclosure shell containing components thereof and having an open end, a base member having a central opening out therethrough mounted in said open end portion of said shell, said member having an arcuate resistivepath placed on the underside thereof, a contactor in sliding relation with said resistive path, a shaft passing through said opening in said base member, a rotor integrally molded to said shaft for rotation therewith, means on said rotor for maintaining said contactor in sliding relation with said resistive path on the rotation of said shaft, means cooperating with said rotor for dividing the resistive path of said control into a predetermined number of resistive steps, and spring means included in said shell opposite said open end portion cooperating with said rotor to provide means for indexing the amount of' resistance encompassed by the rotation of said shell.

3. An electric control device comprising in combination, an enclosure shell containing components thereof and having an open end, a base member having a central opening out therethrough mounted in said open end portion of said shell, said member having an arcuate resistive path placed on the underside thereof, a contactor in sliding relation with said resistive path, a shaft passing through said opening in said base member, a rotor molded to said shaft for rotation therewith, means on said rotor for maintaining said contactor in sliding relation with said resistive path on the rotation of said shaft, means cooperating with said rotor for dividing the resistive path of said control into a predetermined number of resistive steps, said rotor including a plurality of equally spaced detents, and a spring indexing means cooperating with the detents of said rotor to control the amount of resistance in a step by step fashion as the shaft rotates.

4. An electric control device comprising in combination an enclosure shell containing components thereof and having an open end, a base member having a central opening out therethrough mounted in said open end portion of said shell, said member having an arcuate resistive path placed on the underside thereof, a contactor in sliding relation with said resistive path, a shaft passing through said opening in said base member, a rotor integrally molded to said shaft for rotation therewith, means on said rotor for maintaining said contactor in sliding relation with said resistive path on the rotation of said shaft, indexing means cooperating with said rotor for dividing the resistive path of said control into a predetermined number of resistive steps, said rotor comprising a plurality of hemispherical protuberances equidistantly spaced circumferen tially about said rotor and a resilient indexing means included in said shell opposite and adjacent to said detents so that said resilient indexing means cooperates with said rotor to afford posi.

acsasso;

7 tive indexing means for the resistive element on the rotation of said shaft.

- 5. An electric control device comprising in combination, an enclosure shell for containing several components therein, said shell having an open end, a base member having a central opening cut therethrough mounted in said open end portion of said shell, said base member having an arcuate resistive path placed on one side thereof, a contactor in sliding relation with said resistive path, a shaft passing through said opening in said base member, a rotor connected to said shaft and adapted thereby to rotate therewith, said rotor having an undersurface formed as a plurality of detents and an indexing spring mounted in the base of said shell so as to cooperate with said detents of said rotor to index the resistance element of the control.

6. An electric control device comprising in combination, an enclosure shell for containing the several control components therein, said shell having an open end, a base member having a central opening cut therethrough mounted in said open end portion of said shell, said base member having a resistive path placed on one.

side thereof, said resistive path comprising a plurality of separated resistive elements, the separations therebetween being a plurality of interposed conductors, a contactor in sliding relation with said resistive path, a shaft passing through said opening in said base member, a rotor connected to said shaft adapted thereby to rotate therewith, said rotor formed with a plurality of hemispherical detents, and an indexing spring cooperating with said detents so as to provide a switch means utilizing the separate resistive elements of said resistive path in a manner such as to provide a positive indexing therefor.

7. An electric control device comprising in combination an enclosure shell for containing the control components therein, said shell having an open end, a resistive element mounted adjacent the open end of said shell, said resistive element comprising a plurality of separated segments of resistance, said segments being interconnected by means of interposed electrical conductors, a contactor in sliding relation with said resistive element, a shaft passing through said resistive element, a rotor connected to said shaft and adapted thereby to rotate therewith so as to move said contactor along said resistive path, a plurality of detents integrally formed of said rotor and spaced therealong at equidistant points, and spring indexing means positioned adjacent said detents to cooperate therewith so as to provide a positive indexing means for the rotation of said shaft about said resistive element.

8. An electric control device comprising in combination, a casing for containing several control components therein, said casing having open and closed ends, a resistive element mounted in said casing, a rotor for said control, a contactor fitted on said rotor and maintained thereby to make sliding contact with said resistive element, means for rotating said rotor, said rotor being formed with a plurality of hemispherical protuberances opposite said contactor, said protuberances being formed on said rotor at predetermined points circumferentially therealong, and an annular indexing spring mounted next said hemispherical protuberances of said rotor and cooperating therewith to give a positive indexing to said control, said spring being bowed and cooperating with said rotor to give positive indexing to said control.

9. An electric control device comprising in combination, a casing for containing several control components therein, said casing having open and closed ends, a resistive element mounted in th open end of said casing, a rotor for said control, a contactor fitted on said rotor and maintained thereby to make sliding contact with said resistive element, means for rotating said rotor, said rotor being formed with a plurality of hemispherical protuberances opposite said contactor, said protuberances being formed on said rotor at predetermined points circumferentially therealong, and an annular indexing spring mounted next the closed end of said casing facing said hemispherical protuberances of said rotor and cooperating therewith to give a positive indexing to said control, said spring being bowed and having an annular configuration to cooperate with said rotor to give positive indexing to said control.

10. An electric control device comprising in combination, a casing for containing several control components therein, said casing having open and closed ends, a resistive element mounted in the open end of said casing, a rotor for said control, a contactor fitted on said rotor and maintained thereby to make sliding contact with said resistive element, means for rotating said rotor, said rotor being formed with a plurality of hemispherical protuberances opposite the contactor, said protuberances being predeterminedly molded to said rotor at equidistant points therealong, an indexing spring mounted next the closed end of said casing adjacent said hemispherical protuberances of said rotor cooperating therewith to give a positive indexing to said control, said closed end of said casing having a plurality of struck-out portions inwardly extending therefrom, and means on said indexing spring connected thereto to anchor said spring to said casing by means of said cut-out portions formed therein.

11. An electric control device comprising in combination, a casing containing several control components therein, said casing having open and closed ends, a resistive element mounted in the open end of said casing, a rotor for said control, a contactor fitted on said control and maintained thereby to make sliding contact with said resistive element, means for rotating said rotor, said rotor being formed with a plurality of detents opposite said contactor, said detents being formed on said rotor at predetermined points circumferentially therealong, an indexing spring mounted next the closed end of said casing facing said detents of said rotor to cooperate therewith to give a positive indexing to said control, and means centrally connected to said rotor passing through said indexing spring to support said rotor on said closed end of said casing in a bearing fashion.

12. An electric control device comprising in combination, a casing containing several control components therein, said casing having open and closed ends, a resistive element mounted in the open end of said casing, a rotor for said control, a contactor fitted on said control and maintained thereby to make sliding contact with said resistive element, means for rotating said rotor, said rotor being formed with a plurality of detents opposite said contactor, said detents being formed on said rotor at predetermined points circumferentially therealong, a bowed annular indexing spring mounted next the closed end of said casing facing said detents of said rotor to cooperate therewith to give a positive indexing to said control, a pair of struck-out portions formed of said closed end of said casing for maintaining said spring therewithin, and means centrally connected to said rotor passing through said indexing spring to support said rotor on said closed end of said casing in a bearing fashion.

ROBERT J. AUST. WALTER E. PEEK.

REFERENCES CITED The following references are of record in the file of this patent:

Number Number 10 UNITED STATES PATENTS Name Date Read Mar. 9, 1909 Jacobi Apr. 15, 1930 Hathorn Oct. 18, 1939 Schellenger Oct. 24, 1939 Smith Sept. 7, 1943 Arisman et a1 Oct. 11, 1949 Appleton et a1 Aug. 15, 1950 FOREIGN PATENTS Country Date Switzerland Oct. 16, 1948 Germany Sept. 7, 1929 France Jan. 16, 1939 

